Limit switch



Oct .18 1927 c. H. BEcKwrrH LIMIT SWITCH Filed July 22,l 1926 3 Shegats-Sheet 1 IIIIIIl Oct, 1s, 1927.

C. H. BECKWITH LIMIT SWITCH Filed Jul 22, 1926 3 Sheets-Sheet 2 1 1646 11u11 oct. 18,1927. C. H BECKWITH 8 LIMIT swITcH Filed July 22, 1926 3 sheets-sheet 3 Patented Qct. 118, 1927.

UNITED STATES PATENT OFFICE.

CLINTON H. BECKWITH, OF GENEVA, ILLINOIS, ASSIGNOB TO CRANE CO., OF CHICAGO,

ILLINOIS, A. CORPORATION OF ILLINOIS.

LIIIT SWITCH.

Application ma my sa, ma. semi m. medias.

My invention relates to switches, and while the principle of this invention may be uti lized for various control purposes wherein it is desired to operate a motor through a predetermined space of time, for the purpose otl this invention I have shown and will describe the same in connection with a. motor operated gate valve.

For a. better understanding of this invention and the principles of the same, and the connections for the operation of the motor which opens and closes the gate valve, I refer to United States Letters Patent #1,529,005, granted to me March 10, 1925. The principles employed in the switch shown in Fig. 2 of such patent and the wiring diagram, chart, etc., shown in Figs. 5 to 7, are, in principle, the same in this application as in my patent mentioned.

The object of this invention is to pro vide a limit switch which will more effectually carry out the principles set forth in the switch in Fig. 2 of said patent and to render the same more mechanically perfect than the switch therein shown.

To these ends, therefore, the objects and advantages. in addition to the compactness of assembly, economy in manufacture and installation, and the reliability of operation will be readily appreciated as the invention is better understood by reference to the following description when considered in connection with the accompanying drawings, wherein: y

Fig. 1 is a side elevation showing a gate valve with its operating motor and the limit switch attached thereto,

Fig. 2 i-s a front elevation of my improved limit switch with the cover plate removed so as to show the switch details,

Fig. 3 is a vertical sectional view of the switch taken on the line 3-3 of Fig. 2,

Fig. 4 is a view partly in section, and

Fig, 5 is a cross sectional View on the line 5--5 ot Fig. 3.

Like symbols and characteristics herein indicate like parts in each of the figures of the drawing.

Referring to the drawings and particularly to Fig. 1 thereof, reference character 6 indicates the casing of a gate valve which equipped with a valve seat into which a valve (not shown) is adapted to he seated, and said valve is carried on a stem 7 which is provided at its upper end with the usual hand wheel 8 and the other operating parts, such as gears, etc., shown in Fig.\ 1 and described in the specitication of my patent before referred to. The valve is also provided With the gear 9 meshing with the gear 10 on the shaft of the motor 11, which motor is supported on the bracket or yoke 12 of the valve. On the opposite side of the valve is the switch 13 which is operated through the gear 14 attached to the screw shaft 15 and meshing with a pinion (not shown) adapted to be operated so as to turn the shaft 15.

The switch 13 is housed in a box 16 which `is provided with ears 17 through which holes 18 extend for the reception of bolts for fastening the said box to the yoke of the valve as shown in Fig. 1, and said box is provided with a cover plate 19 and between the said cover and the box sides and ends 16 a rubber gasket 21 is placed so as to provide for a gas-tight interior in the box 16.

This cover 19 is heldonto the box 1 by suitable bolts 22 threaded into the holes 23 in the bosses 24 on the interior of the box. The screw shaft 15 extends through the boss 26 and upper end of the box 16 and entirely through the-interior of the box where the reduced end 27 thereof is journaled in ahoss 28, while at a position contiguous'to the said boss and at a position contiguous to the boss 29 at the upper end of the box, the screw shaft is 'provided with limiting collars 31 which are heldin place by pins 32 extending through the same and Athrough the said screw shaft s0 that there can be no vert-ical movement of the screw shaft within the box.

The outer annular face of the boss 26 is provided with screw threads 33 for the reception of a packing nut 34, while the interior of said nut is provided with a quantity of material 36 which is pressed tightly around the said shaft and against the upper end of the boss 26 by the rotation o said nut, so that no gas or air can enter the said boss around the screw shaft 15. The screw shaft 15 is provided with threads 37, the purpose of which is hereinafter explaine At the left hand side, see Fig. 2, of the screw shaft 15 within the box 16 is a block 38 formed of fiber, a phenolic condensation product, or some other non-electrical conductive material, and this block is held in position by suitable screws 39 extending through the same into the bottom of the said box.

Mounted upon the block 38 are two wiping contact units which I havedesignated generally as a and b. Each of these members consists of a pair of angular shaped members 43 which have an attaching portion 44, by which they are secured to the said blocks and an outwardly extending portion 46. Each of said members 43 is also provided with suitable holes for the reception of the binding posts 47 for attaching thereto a lead 48 from any source of power.

The outwardly extending portions 46 of the members 43 are disposed toward each other and are each provided with a pin 49 which has a contact arm 51 loosely fitting over the same, while the inner end 52 of said contact arm is bent at right angles to that portion which fits onto the pin 49 and which is designated by the numeral 50. Such rightangular portion 52 extends into a groove or slot 53 on the inner face of -the outwardly extending portion 46 of the member 43, while the other end of said contact member is shaped to receive in cooperation with the member 51 a contact sleeve 54 in order to form a. contact between the arms 51 and 51.

Located slidably on the pin 49 and resting against the portion 50 of the contact arm 51 is a spring cup 56 in which one end of a spiral spring 57 rests while the other end of said spring rests in a spring cup 58 on the outer end of said pin and is prevented from leaving the same by the eotter 59 extending through the pin, while the spring 57 will exert tension between said cups, so that the portion 50 of the contact arm will always have its right angled end 52 pressed into the groove 53, and the portion 50 will always rest against the corner of out- Wardly extending'portion 46 of the member 43, where I have placed the numeral 55, except when the same is pressed outwardly therefrom by the contact sleeve 54.

- On the right hand side, see Fig. 2 of the screw 15 are two wiping contact units, designated by the characteristics c and d, and these members are mounted on blocks 61 and 62 respectively, formed ofthe same material as the block 38, and are held in position by means of screws 63 extending 'through the same and into the bottom of the box. Each of these wiper contact members is provided with the contact arms 51 and 51 held in position on the pins 49 as explained in connection with the wiper contact units a and .6, the construction being the same in each individual case. These blocks 61 and 62 are preferably disposed at angular relations with respect to the block 38, and the said Contact arms 51 and 51 preferably extend substantially perpendicularly to one side or face of the blocks 61 and 62 for the purpose of receiving the contact sleeve 54 between the outer ends of the same when it is swung on its pivotal connection 64, as later explained.

The bottom of the box 16 is provided with two small pads 66 located one above the block 38 and the other at a point below the same. Into each of these pads a post 67 is fitted by its reduced portion 68, and the ends thereof riveted as shown in Figs. 4 and 5. This post is provided with a hole 69 extending from its upper surface into the -center of the same, and a slot 71 extends across the face of the same for the reception of the rib 72- located on the body 73 of the swinging member 74. This body 73 has a hole 76 extending through the center of the same, while a shaft 77 extends through said hole 76 and into the hole 69, and is pressed or forced into the hole 69 so that it cannot be withdrawn therefrom. The body 73 is provided with an arm 78 which has its under face 7 9 formed to provide a cam, while at a position substantially at right anglesto said arm 78 is a small arm 81, into the lower face of which is securely fitted a small depending post 82 which has an annular groove 83 near the lower end of the same for holding one end of a spiral spring 84 'which extends around a partof the body 73 and a part of the post 67, while its other end is secured in the annular groove 86 of a post 87 secured in the bottom or baclvwall of the box 16. Diametrieally opposite to the small arm 81 is an arm 74 which has an Ogee curve 89 in the same to provide proper clearance for the operating parts of the switch member, and has an outer elevated end 91 carrying thereon a vertical post 92 which is either formed integrally with, or firmly mounted in the said arm. This post .is rovided with a sleeve 93 of insulation whlch completely covers the periphery of the same, and an insulating collar 94 is fitted around the said sleeve 93 at its lower end` and in proximity to the portion 91 of the arm 74 another insulating collar 96 is fitted around the said sleeve 93 at its upper end, while between the two collars and around the insulating sleeve 93 is a copper sleeve 97 which forms a contact with the contact arms 51 and 51 of the wiping contact members, as later explained.

These several sleeves and collars are held securely in the positions described by means of a washer 98 held on the end thereof by means of the set screw 99. Above the body 78 of the switching member 74 and around the shaft 77 is a spiral spring 100 whose upper end fits into a spring cup 101 held in position by a Cotter pin 102, so that the body 78 which fits loosely on the shaft 77 will be normally urged downward by the tension of the said spring in order to keep the rib 72 with the slot 71 in the upper face p tened together. provide a longitudinal recessl08 which its over a rod 109 which extends the entire height of the box 16, and has its upper end secured in the hole 111 1n the upper end of the said box, while its lower end extends into a hole 112 in the lower end of said box and said rod is held in position by means of a plug 113 screwed into a threaded hole 114 in the lower end of said box and aga-inst the bottom of said rod. This rod `will prevent the cam operating member 103 from turning or twisting from the position such as shown in Fig. 5, so that its outer curved end 11,16 will always be in a position to engage the cam 79 of the swinging member 74 when the screw 37 is operated to lower the said cam operating member thereon.

For the urpose of illustrating and describing the operation of my improved switch, let us consider the cam operating member located on the lower end of the screw shaft 15 and the switching member 74 which the said cam operatin member operates. Considering the parts 1n the position shown in Fig. 2 and the contact sleeve 54 in engagement with and forming a contact between the contact arms 51 and 51 of the wiping contact unit b, the screw shaft is now rotated by the gear at the upper end of the same, which is not shown but which was herein described, so that the cam operating member 103 will be moved downward on the said screw shaft. Its outer curved end 116 will come in contact with and engage the cam 79 on the arm 78, and the body 73 will be raised against the action of the spring 100 above the said body and surrounding the shaft 77. As the body is thus raised, the rib 72 in the bottom of said body will be withdrawn from the slot 71 in the upper face of the ost 67, and when the same has been comp etely withdrawn therefrom, the entire swin ing member 74 is free to rotate on the shaft 7, and the spring 84 is adjusted on the posts 82 and 87 so that iturges the said swinging member to rotate in a direction shown by the arrow on Fig. 2.

The swinging member, therefore, by its rotation, will withdraw the contact sleeve 54 from between the contact arms 51 and 51 on the wiping contact b and will throw said contact sleeve around so that it will enter between the contact arms 51 and 51 of the wiping contact d, while the cam 79 will be turned around out of engagement with the cam operating member 103.

lVhen the screw shaft 15 is operated in the reverse direction, and while the .contact sleeve 54 is in engagement with the contact arms 51 and 51 of the wiping contact d, the cam operating member 104 will rise on the said screw sha-:tt by reason of its thread- ,ed interior 106 engaging with the threads 37 on said shaft and the said vcam operating member will bear against the portion 119 of the arm 74 and will press the contact sleeve 54 out of engagement with the contact arms 51 and 51 of the lcontact d, and as the said cam operating member bears against the ogee-portion 89 of said arm, the contact sleeve 54 will be thrown to the position shown in Fig. 2. At this momentthe rib 72 will be in line with the slot 71 on theouter face of the post 67, and as the cam operating member is merely bearing against the portion 119 of the arm 88 and is not in engagement with the cam 79, the spiral spring 100 will exert pressure upon the upper end of the body 7 8, so that the said rib 72 will be forced into the slot 71 and thus held from turning until such time as the cam operating member again engages the cam 79 to lift the body 78 and thus withdraw the rib 72 in engagement with the slot 71. l

During the downward movement of the cam operating member 103 which operates the contact sleeve 54 for the contact thereof, the cam operatingmember located on the upper part of the screw shaft '15 has been descending to press the arm 74 around to disengage the contact sleeve 54 from the arms of the wiping contact c and'into engagement with the contact arms on the wiping contact a and vice versa.

The simultaneous operation of the upper and lower swinging arms 74 can be arranged by placing the cam operating member 103 of the upper member above the cam 79 on the arm 81 instead of below the same as it is shown on the drawing, and particularly on Figs. 2 and 3.

It will readily be seen that additional mechanisms may be operated through the screw shaft 15 by placing additional cam operating members upon the said shaft, and while I have shown but two switches in the accompanying drawings, I do not limit myactuating sai the parts are so constructed and assembled that there is practically no danger of the same becoming inopertive at any time.

Various modifications, adaptations. and

uses of my invention will undoubtedly suggest themselves to those skilled in the art, so that it will be obvious that many changes in the construction and shape of parts, connections, number of switches, and design and uses of my invention may be resorted to without departingr from the spirit of the invention and sacrificing any of its advantages, the scope of which is defined in the following claims.

I claim:

1. A limit switch comprising a movable contact member, a plurality of contact units for the reception of said member, a screw shaft, meanspropellable by said shaft for actuating said member, means for locking said member in a predetermined position, and means connected with said member normally tending to urge it from said predetermined position.

2. A limit switch comprising a movable contact member, a pluality of contact units for the reception of said member, a screw shaft, means for locking said member in a predetermined position, and means propelable by said screw shaft for unlocking said member.

3. A limit switch comprising a movable contact member, a plurality of contact units for the reception of said member, a screw shaft, means ropellable by said shaft for d) member, means for locking said member in a predetermined position,` means connected with said member normally tending to urge it from said predetermined position, and means propellable by said shaft for unlocking said member. 4. A limit switch comprising a movable contact member, a plurality of contact units for the reception of said member, a screw shaft, means for locking said member in electrical contact with one of said units, and means propellable by said shaft for moving said member into said locked position.

5. A limit switch comprising a movable contact member, a plurality of contact units for the reception of said member, a screw shaft, a control member disposed on and propellable by said shaft, means for locking said Contact member in a predetermined position, said contact member adapted to be unlocked by the movement of said control member, means for urging said member into 'contact with another unit upon the unlocking of the same, said member being adapted to be returned to its locked position by the movement of said control member in a rea plurality of contact units for the reception o said member, means for locking said member in a predetermined position, a control member, and means for propelling said control member, said control member being adapted to -unlock said contact member.

7. A limit switch comprising a movable contact member, a plurality of contact units for the reception of said member, means for locking said member in contact with a. predetermined unit, a control member, means for propelling said control member to thereby unlock said contact member, and means connected with said contact member for effecting a quick break of contact between said member and said predetermined unit.

8. A limit switch comprising a movable contact member, a plurality of contact units for the reception of said member, an actuating spring normally tending to rotate said member in one direction, means for locking said member in one of said units, means for unlocking said member, and means for rotating said member into said position.l 9. A limit switch comprising a movable contact member, a plurality of contact units for the reception of said member, means for locking said member in one of said units, means connected with said member normally tending to urge it from said position, a control member adapted to unlock said contact member, propelling means for moving said control member, and means for adjusting said control member on said propelling means.

10. A limit switch comprising a movable contact member, a plurality of contact units for the reception of said member, an actuating spring normally tending to rotate said member in one direction, means for locking said member in one of said units, means for unlocking said member to permit said sprin to urge said member into another of sai contact units, and means for returning said member into said locked position.

11. A limit switch comprising a movable contact member, a plurality of contact units alternately closed and opened by said member, a screw shaft, a cam on said contact member, means for locking said contact member in a predetermined position, and a cam operating member adapted to engage said cam to unlock said contact member when said shaft is rotated.

12. A limit switch comprising a movable contact member, a plurality of contact units alternately closed and opened by said member, a screw shaft, a cam on said contact 1 member, means for locking said contact member in a predetermined position, and a cam operating member adapted to engage said cam to unlock said contact member when said shaft is rotated and to return said cont-act member to its locked position when the rotation of said shaft is reversed.

13. A limit switch comprising a stationary member, a movable contact member mounted on said stationary member, a plurality of contact units adapted to be alternately closed and opened by said member, a rib on one of said members, the other ot said members having a slot therein, a screw shaft, means normally holding said rib in said slot, and means on said shaft for disengaging said rib and slot to permit said Contact member to be moved.

14. A limit switch comprising a stationary member, a movable contact member mounted on said stationary member, a plurality ot contact units adapted to be alternately closed and opened by said member, a rib on one of said members, the other of said members having a slot therein, a screw shatt` means normally holding said rib in said slot, a cam on said body, and a cam operating member adapted to engage said cam to un lock said contact member when said shaft is rotated.

15. A limit switch comprising a body, an arm on said body, a contact member on said arm, a stationary member having a slot therein, a, rib n said body. a plurality of contact units adapted to receive said contact member, means normally urging said rib into said slot to lock said contact. member in one of said units, a screw shaft, and means operated by said screw shaft to disengage said body and stationary member.

16. A limit switch comprising a body, an arm on said body, a contact member on said arm, a stationary member having a slot therein, a rib on said body, a plurality of contact units adapted to receive said contact member, means normally urging said rib into said slot to lock said contact member in one of said units, a screw shaft, means operated by said screw shaft to disengage said rib from said slot, and means for throwing said contact member into engagement with another switch when ,said rib is withdrawn :from said slot.

17. A limit switch comprising a body, an arm on said body, a contact member on said arm, a stationary member having a slot therein, a `rib on said body, a plurality of contact units adapted to receive said contact member, means normally urging said rib int-o said slot to lock said contact member in one of said units, a7 cam on said body, a screw shaft, and means on said screw shaft engaging said cam for withdrawing said rib from said slot upon the rotation of said shaft.

18. A limit switch comprising a body, an arm on said body, a contact member on said arm, a stationary member having a slot therein, a rib on said body, a plurality of contact units adapted to receive said contact member, means normally urging said rib into said slot to locksaid contact member in one of said units, a screw shaft, means operated by said screw shaft to disengage said rib from said slot, and means for throwing said contact member into engagement with another unit when said rib` is withdrawn from said slot and adapted to engage said arm to throw said contact member into its original position upon reversing the direction of rotation of said screw shaft.

19. A limit switch comprising a body, an arm on said body, a contact member on said arm, a stationary member having a slot therein, a rib on said body, a plurality of contact units adapted to receive said contact member, means normally urging said rib into said slot to lock said contact member in one of said units, a cam on said body, a screw sha-ft, and means on said screw shaft engaging said cam for withdrawing said rib from said slot upon the rotation of said shaft and adapted to engage said arm to throw said contact member into its ori al position upon reversing the direction o rotation of said screw shaft.

In witness of the foregoing I aix my signature.

CLINTON H. BECKWITH. 

